The present invention relates generally to cartridges containing a continuous loop of ribbon, especially fabric ribbon, for use in printers associated with equipment such as computers and word processors. More particularly, the present invention relates to apparatus employed in loading assembled cartridges with inked printer ribbon. Still more particularly, the present invention relates to an apparatus for supplying measured lengths of leader ribbon used in the assembly and loading of printer ribbon cartridges.
Present society is highly dependent on the use of microprocessors, minicomputers, and mainframe computers. In addition to the more traditional use of computers as a research tool, computers are now often found in the home environment and work environment of individuals who, until recently, never before came into contact with a computer. Computers are used to automate equipment in a manufacturing facility, to automate secretarial duties at the office and to automate a myriad of toys and tools around the home.
All computers, whether mainframe computers, minicomputers or microcomputers, share a common requirement for some means of communication with users. Such means of communication may vary from a simple light-emitting diode (LED) to the complex cathode ray tube (CRT) terminal. A common means for communication of information from a computer to a user is a printer. Printers typically receive from a computer a stream of information in the form of digital electronic signals and convert the electronic signals to a series of symbols (letters, numbers and words) printed on paper.
A first common type of printer is an impact printer, so named for the means by which characters are printed on paper. Each symbol which the impact printer is capable of generating is permanently embossed on a striking surface (analogous to the ball within a typewriter) within the printer. The printing of a particular character is accomplished by aligning the embossed image of that character with the paper surface onto which the characters are to be printed, positioning a printer ribbon having ink thereon between the striker and the paper, and causing the striker to impact the ribbon against the paper surface so as to result in an ink image of the embossed character on the surface of the paper. Printer ribbons typically are made of fabric, such as nylon, or polyester film coated with a carbon-type surface.
A second common type of printer is a dot matrix printer. Such a printer includes a group of small-diameter wires oriented parallel to one another and arranged in a two-dimensional matrix. Each wire is arranged for independent extension from its normal matrix position to contact a printer ribbon, thereby printing a dot image on an adjacent paper surface. By selectively extending particular patterns of wires, dot images can be combined to form alphanumeric or other legible characters on the paper surface.
In approximately 1970 there first appeared on the market a printer ribbon having the ends thereof adjoined to form a continuous loop. The continuous loop ribbons are housed within cartridges which easily may be removed from and inserted within the printers. Such continuous loop cartridges mechanically simplify the ribbon control portion of printers and thereby eliminate a potential source of printer failure.
A number of companies throughout the world today are engaged in the business of manufacturing and/or loading printer ribbon cartridges. Printer ribbon cartridges are typically assembled manually, and are assembled before they are loaded with printer ribbon which is generally delivered to the cartridge manufacturer uninked or inked and spooled into large, narrow rolls.
In order to subsequently load the assembled cartridge with printer ribbon, the cartridge may be assembled with a length of leader ribbon threaded through the cartridge's housing. The ends of the leader ribbon are left extending outside the assembled cartridge. These exposed ends of the leader ribbon may then be attached to inked printer ribbon and the leader ribbon used by the cartridge drive members or an external drive member to draw the appropriate length of printer ribbon into the previously assembled cartridge. One such apparatus particularly useful in automatically stuffing the assembled cartridge with inked printer ribbon is disclosed in U.S. Pat. No. 4,609,422, issued Sept. 2, 1986.
To date, it has been the conventional practice to manually measure and sever the required lengths of leader ribbon from a supply reel or spool of such ribbon. Because this process of supplying measured leader lengths is performed manually, it is subject to operator errors both in the step of measuring the appropriate leader length, and in the step of cutting the ribbon at the appropriate location. The likelihood of errors is increased due to the time pressures that competitive forces place on the cartridge manufacturer's labor force.
In manufacturing printer ribbon cartridges, it is critical that the cartridges be assembled with the proper length of leader ribbon. If the cartridge is assembled with a leader that is too short, the stuffer apparatus will not be able to load the cartridge with inked ribbon, requiring the operator to remove the defective cartridge, replace it with another and again ready the stuffing apparatus for the loading of a cartridge. As is evident, a cartridge having a leader that is too short causes costly delays in the stuffing of the assembled cartridges and in the ultimate production of printer ribbon cartridges. In addition, the defective cartridge must either be discarded, resulting in material waste, or reassembled, resulting in additional labor costs.
Similarly, if a cartridge is assembled with a leader ribbon which is longer than that required by the stuffing apparatus, an operator is required to manually jog the drive motor in the stuffer apparatus in order to take up the excess leader length prior to initiating the stuffing cycle. Once again, the extra operator interaction delays the stuffing process and the ultimate production of finished cartridges. All such delays and output reductions directly affect the manufacturer's profitability.
As is readily apparent, certain inadequacies exist in the present method and apparatus that are employed to supply the lengths of leader ribbon for use in assembling and loading printer ribbon cartridges. An apparatus which would accurately measure and sever the appropriate leader length from a ribbon supply and do so automatically with a minimum of operator involvement would be a welcomed addition to this art. Further, an apparatus which could store the severed leader length in a convenient position for use by the operator in assembling the cartridge would be an additional benefit. Ideally, the apparatus should be able to accommodate all types and widths of printer ribbons and would be easily adjusted so as to supply the varying lengths of leader ribbon needed for the different cartridge configurations.